Who to tip? How much?
These are questions that go back generations.
At the end of the 19th century, it was a huge controversy.
"There was probably not a newspaper you could pick up or a magazine that you could pick up, in the late 19th and early 20th century, and flip through it for a few pages, and not find an article about tipping," said Andrew Haley, a history professor at the University of Southern Mississippi, and author of "Turning the Tables: Restaurants and the Rise of the American Middle Class."
Middle class diners wrote editorials against tipping. They boycotted. Some places outlawed it.
"Six states passed anti-tipping laws in the early 20th century," Haley said, "and at least four other states were considering similar laws.”
Over time, Americans got used to tipping and settled on some basic rules.
"The norm is very clear," said Mike Lynn, a marketing professor at Cornell University School of Hotel Administration, "you tip 15 percent to 20 percent to waiters and waitresses." That, he says is pre-tax, and it includes beverages and wine.
"There are norms for tipping other service providers," Lynn said, "but they are even less well known than the restaurant norm."
So, what's the norm for a coffeehouse like Starbucks?
Lynn paused. He sighed. "I don’t know," he said.
Everyone does something a little different -- no tip, tip all the time, tip when they get food.Marketplace has a poll, too. Of the nearly 550 responses so far, most don't tip. Those who do, tend to tip $1. Ten people said they'll just drop whatever change they get back into the tip jar.
It's possible the Starbucks app could start to set a norm.
Some of that will depend on how the app works, said Holona Ochs, a professor at Lehigh University and co-author of "Gratuity: A Contextual Understanding of Tipping Norms From the Perspective of Tipped Employees." If the app asks you how much you want to tip, with suggestions, like the screens in the back of cabs do, "then it’s a signal that you are required to tip, even if the service was poor."
The more people are encouraged to tip, the more likely they are to give one.
But, should customers be tipping baristas at all? Why are hair dressers tipped, but not mechanics? There are a number of theories out there.
"Economists would say we tip those service providers where it is more economically efficient for the customer to monitor and reward employee behavior than for the firm to do it," Lynn said. Different customers want to be treated differently; people tip in circumstances where the customer is in the best position to determine who did a good job.
Anthropologists have a different theory about who gets a tip.
"We tip to avoid envy," explained Lynn. "My car mechanic doesn't envy me because I had a broken car."
But the server might. "When I go out to eat, I'm having a good time," said Lynn. We don’t want to be the subject of envy. So we give a tip to say "don't envy me, have a drink on me later."
Lynn says the small amount of data that exists suggests a third explanation: people tip more when they think there’s a greater income disparity between server and the customer. And when they have more personal contact with the person they’re tipping.